As children across the country returned to their first day back in the classroom since 20 first-graders and six adults were gunned down at Sandy Hook Elementary in Newtown, Conn., parents probably took a second look at the doors and fences that are supposed to keep their kids safe. If they hadn’t thought much about school security before the Sandy Hook tragedy, they are certainly thinking about it now.

I know I was. My youngest daughter typically files into school with her kindergarten classmates, her big backpack overwhelming her little body. On Monday, I walked her in. I hugged her, whispered “stay safe,” then continued on to the office. After Sandy Hook, I asked the secretary, are we rethinking school security?

At my daughters’ public school in Washington state, there is next to none. The front door remains unlocked throughout the day; visitors are supposed to sign in at the office but no one enforces that. (I know; I’ve skirted the policy myself many times when I’ve been in a hurry to drop off something they have forgotten.) The situation is even worse at my son’s school, where visitors enter without being seen by anyone in the office, which is tucked away from the entrance. His former public school in North Carolina swung to the opposite extreme: all guests were met at the entrance by a security guard, who photographed them and required an ID before printing out a badge that had to be worn while in the school. Meanwhile, in the New York school system, my aunt has to pass by surveillance cameras to reach the classroom where she teaches.

The Sandy Hook massacre has exposed security gaps and widely disparate safety procedures in public school systems across the country, highlighting a lack of across-the-board guidelines. Federal efforts to develop stronger emergency response plans, such as the Readiness and Emergency Management for Schools grants that cover security, have been financially curtailed in recent years, the Christian Science Monitor reports. To fill the void, National PTA and the American Academy of Pediatrics (AAP) are eager to issue guidance. It’s a matter that has long been open for debate: school security isn’t set by any one governing body; it’s decided upon by individual school districts. In the U.S., there are more than 13,000 so it stands to reason that policies vary widely, even within states. Some states, such as Florida, check visitors’ IDs against a national database of sex offenders; others also confirm that a court order hasn’t barred a parent from seeing a child. Many districts, including Seattle, don’t check IDs at all.

Ultimately, however, security often comes down to funding. “A lot of states were pushing for funding for school security and equipment and security audits, but when the economic bottom fell out in 2008, it all got put on the back burner,” says security consultant Steve Wilder.

Now, Friday’s unthinkable tragedy may have shifted priorities back to finding strategies for keeping kids safe. “It’s unthinkable that we have rules and regulations in all sorts of places but we can’t seem to find the money to protect our kids in their schools,” says Dr. Bob Block, immediate past president of the AAP. “What we want is for students in their schools to know they’re secure so they can focus their attention on lessons rather than looking over their shoulder to check out everyone who comes into their school.”

What could make that happen? Ideally, security experts say, schools should have a “man-trap,” a set of outer doors that leads to a vestibule with a screening point and a set of inner doors beyond which visitors can’t go unless they are vetted. Doors should remain locked, safety drills should take place without warning and parents should be informed of where they should collect their kids in an emergency.

All schools should have reinforced plate glass and “access control,” a term experts use to refer to limited entry. That means schoolyards should be completely fenced, as they are in the U.K., with visitors buzzed in through a central gate. That’s a particular challenge, say some administrators, since many schools are designed with an open-access philosophy to encourage learning and foster a welcoming atmosphere for students.

Such technology, along with reinforced ground-floor windows and doors is only a first step, however; staff training maybe be even more important. “We see some schools spending thousands of dollars on systems that ‘read’ access cards, but in the end the users are the breakdown,” says Wilder, who has performed security audits on more than 100 schools. “Inevitably someone props open the door to the kitchen or the gym.”

Drills are also a critical part of security preparation, but too many schools announce them ahead of time, giving teachers and students time to prepare. “Realistic drills are unannounced,” says Wilder.

Meanwhile, National PTA leaders are combing through various resolutions the organization has issued on school violence, mental health and gun control to decide which issues to prioritize: should they lobby for security guards in every school? Tougher gun-control laws? Adequate mental-health treatment for all students? “We’re trying to wrap our head around everything that’s happened, pull together our positions and figure out what we can do to move this conversation forward,” says spokesman James Martinez.

Three days after the Conn. shooting, the organization sent an email to its state offices alerting them of an upcoming advocacy plan: “Rest assured, we fully plan to engage our powerful network of nearly 5 million dedicated members to make a difference on this issue.”

Students may also play an integral role in ensuring their own security. Programs such as A.L.I.C.E. — Alert-Lockdown-Inform-Counter-Escape — encourage teachers and children to do more than lock the door and sit quietly if an armed intruder enters their school. Developed by a former SWAT officer, A.L.I.C.E. teaches students to fight back by throwing things at an attacker. About 300 schools and universities have adopted the program, its founder told ABC News, but it remains controversial.

Still, the AAP believes that students can serve as the first line of defense, much as schools have taught students to pay close attention when friends threaten suicide. Last week, for example, a student alerted authorities about a Bartlesville, Okla., high schooler who had researched the Columbine High School shootings and apparently planned to slaughter students in his school’s auditorium. That information led to the arrest of Sammie Eaglebear Chavez; he was charged with conspiring to perform an act of violence on Friday, the same day that alleged Sandy Hook gunman Adam Lanza charged into two classrooms. “The boy who turned him in had the courage and good sense to report that,” says Block. “Even in elementary school, older students should know that if they hear someone talking about having a gun in their locker, they need to tell a teacher. It’s not tattle-taling.”

No security measure is perfect; Sandy Hook principal Dawn Hochsprung — one of the first victims — had recently introduced a new system to lock the school’s doors at 9:30 a.m. and require office sign-in. That didn’t deter Lanza, who reportedly shot his way into the school. But some experts say that the additional time it took him to break past the locked door may have given teachers and students inside time to take cover. “There are no absolutes,” says Michael Dorn, executive director of Safe Havens International, which develops school-safety plans. “But you can significantly reduce risk.”

Even if school officials find a security strategy they feel is effective, they face one remaining hurdle — parents. In one rural county, a superintendent has been trying for more than a year to get approval for every visitor to be individually buzzed in. “Parents haven’t wanted it because they say it’s creating a prison-like environment,” says Dorn, who declines to name the superintendent with whom he has been working. “But that was prior to Friday. That discussion will look very different now that we’re suddenly shocked to the core.”